Easy, lower-sugar, jam made with blueberries, Thomcord grapes, and no added pectin.
Course Preserves
Cuisine American
Keyword Jams
Prep Time 10 minutesminutes
Cook Time 40 minutesminutes
Macerating/Resting 2 hourshours
Total Time 2 hourshours40 minutesminutes
Author Elizabeth at thewildolive.org
Ingredients
8ozThomcord Grapeswashed and destemmed
1.75lb(28 oz total) blueberriesfrozen is fine
2cupssugar
2Tbsp.fresh lemon juice or ½ tsp. citric acid
Instructions
Prep the Fruit
If you are using frozen berries let them partially thaw. Pulse grapes in food processor until coarsely chopped. Add HALF the blueberries and pulse a few times, till blueberries are coarsely chopped. Do NOT puree the fruit!
Preparing the Jam Mixture
In a large, wide, heavy, stainless steel pan combine the chopped fruits, the rest of the whole blueberries, sugar and lemon juice (or citric acid). Stir to combine and let the mixture rest 30 minutes – the sugar does not need to dissolve.
After 30 minutes, gently press fruit mixture with a potato masher till all blueberries are lightly crushed. Stir until sugar fully dissolves. Let the mixture rest another 90 minutes, stirring every 30 minutes. Don’t cheat this rest period or your jam may struggle to set, and you don’t want to go to all this bother to make soupy jam.
Cooking the Jam
During these two hours, get your hot water bath set up and sterilize your jars and lids.
Place pan with fruit mixture over high heat and bring to a boil while stirring. Once the mixture boils, turn the heat down a bit and stir frequently to prevent scorching and boiling over. The mixture will begin to foam a bit on top as it cooks. You can skim the foam or just wait for it to subside, which it usually does.
As the mixture cooks and thickens, it will turn a gorgeous deep purple. Cook fruit, scraping the sides and bottom of the pan every minute or so until mixture reaches the gelling point.
Knowing When Your Jam is Done – Temperature Test
Technically speaking, the gelling point for jam is reached at 8 degrees above the temp at which water boils at your altitude. If you have an accurate instant-read thermometer, simply take the temperature of the rapidly boiling water in the hot water bath you are prepping, and add 8 degrees. You will cook your jam until it reaches that temperature.
Knowing When Your Jam is Done – Plate Test
If you don't have an accurate instant-read thermometer, you can still make this recipe. One method to test doneness is the “plate test”. Before cooking your jam, place a saucer in the freezer. When the jam begins to thicken, start testing. To test the jam, remove pot from heat and place 1 tsp. jam on plate in freezer; wait 1 minute. Take plate out of freezer and lightly push jam with finger – if the surface "crinkles" it is done. If Jam is runny, continue cooking jam and retest.
Once you've made jam a few times, you will be able to tell just by looking at it in the pot if it is done. When you take properly cooked jam off the heat and let it cool for a moment, the mixture will "crinkle" on the surface when you drag a spoon across the top.
Processing the Jam
When jam tests done, ladle hot jam into sterilized half-pint (8 oz.) jars, leaving ½” headspace. Using a stainless steel funnel makes this task a snap! You should have at least 4 if not 5 half-pints of jam. If your fifth jar isn't quite full, do not process it in the boiling water bath. Simply pop on the lid, let the jam cool a bit and put it in the fridge to enjoy first.